Detection and measurement of motion in the human body has been conducted based on Doppler shift phenomenon using ultrasound techniques. An ultrasonic Doppler detection apparatus operates by transmitting an ultrasonic-wave pulse having a known frequency into the human body at predetermined intervals. A reflected signal, such as an echo signal, from a moving reflective object, such as a blood corpuscle is then received. The phase shift i.e., Doppler shift, between the transmitted and received signal indicates motion velocity.
Blood flow in the small blood vessels is an indication of the regulation of the metabolic, hemodynamic and thermal states of an individual. Thus, there are many situations in routine clinical medicine where measurements of blood flow are useful. Ultrasound equipment used for blood flow detection based on Doppler effect is disclosed in U.S. Pat. Nos. 4,534,357, and 5,035,245.
The measurement of blood flow can generally be done only by health professionals or those with substantial medical training. For example, it is rather difficult to properly orient and position the ultrasound transducer on the patient corresponding to the desired location where blood flow is to be monitored. This is because these devices typically employ ultrasonic waves that are transmitted from and received by the device in a “straight line” manner, meaning the transmitting and receiving waves are parallel to each other. U.S. Pat. No. 5,680,865 discloses an ultrasound probe for use in medical examinations to obtain information on in-vivo motion and specifically on blood flow, capable of scanning a region of interest. The scanning is achieved by employing an electric motor for driving the Doppler ultrasound transducer into the target position.